Food product with a fibrous texture obtained from whey proteins

ABSTRACT

Food product obtained by extrusion baking of a mixture of dairy or cheese origin with a fibrous structure characterized in that the fibers form a network of macroscopic fibers whose diameters are in the order of 0.1 mm to 1 mm, ramified into microscopic fibers with diameters in the order of 1 μm to 0.1 mm, with the dry matter of the product at least partially originating from whey.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This present application is a divisional of U.S. patentapplication Ser. No. 09/590,979 filed Jun. 9, 2000, claiming priority toFrench Patent Application Serial No. 9907433 filed Jun. 11, 1999, bothof which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention concerns food products with a fibroustexture, obtained mainly from whey proteins, a manufacturing process byextrusion baking of these products and a manufacturing installation forapplication of the process.

BACKGROUND OF THE INVENTION

[0003] Processes for the manufacture of dairy products by continuousextrusion are already known.

[0004] Document EP-A-727 138 describes one such extrusion process bymeans of which cheese or cheese products are obtained from a curd ormilk fraction resulting from ultrafiltration of milk. The process iscomprised of the following stages: introduction of raw materials,transfer into a barrel with at least one zone in which the temperatureis between 60° and 120° C. involving blending, texturing and baking.This process gives rise to products with stretched structures whosefibres have a diameter that is generally greater than 0.1 mm and in theorder of millimeters.

[0005] Document WO-96/34 539 describes a process used to obtain atextured protein matrix containing a dispersion of inclusion bodies.These products are obtained by means of a high-temperature extrusionprocess, notably at temperatures of 125 to 160° C. High temperaturessuch as this lead to the destruction of the initial protein mixture. Theproducts obtained include protein fibres which are stable after cooling.This document essentially describes the use of vegetable proteins suchas soya.

[0006] Document WO-96/25051 describes a process for the manufacture of asoft or semi-soft fibrous cheese. The fibrous mass is obtained afterextrusion of the curdled milk. These processes do not allow a cheese ormilk mixture to be used to obtain a product with an extremely finefibrous structure, comprising fibres whose sizes are in the range of μmto 0.1 mm, noticeable when the product is chewed and conferring on itoriginal organoleptic characteristics.

[0007] Document U.S. Pat. No. 4,156,028 also describes a process for themanufacture of fibre products whose fibres have diameters in the orderof 100 μm for example. However, these products are obtained by atechnique which involves dissolution followed by a coagulation bath; theprinciples and materials of this technique are considerably differentfrom extrusion baking which brings together specific pressure andtemperature features. The products obtained do not have a ramifiednetwork structure such as that described below.

SUMMARY OF THE INVENTION

[0008] The present invention concerns food products with a fibroustexture, obtained mainly from whey proteins, a manufacturing process byextrusion baking of these products and a manufacturing installation forapplication of the process. A first aspect of the invention proposes aproduct obtained by extrusion baking of a mixture of dairy or cheeseorigin. This product has a fibrous structure with a network ofmacroscopic fibres whose diameters are in the order of 0.1 mm to 1 mm,ramified into microscopic fibres with diameters in the order of 1 μm to0.1 mm, the dry matter in the product being at least partially obtainedfrom whey. The dry matter in the product typically comprises 30% to 100%of dry matter originating from whey. The product consists of 15 to 50%of dry matter and typically 25 to 40%. The dry matter of the productconsists of at least 35% of total proteins. The dry matter originatingfrom whey includes isolated and/or concentrated proteins, and/or driedwhole whey, and/or dried whey fractions such as lactose, milk fats,lactoferrin, calcium or other milk minerals or fractions.

[0009] According to a second aspect, the invention concerns a foodpreparation incorporating a product in keeping with the descriptionabove added to various ingredients chosen from among cheeses, milk andderivative products (yoghurt, milk cream, milk powder, fromage blanc,butter), cereals, starches, flour, semolina, fruits and dried fruits,spices, seasoning, fats, flavouring, sugar-containing ingredients(sugar, honey), pieces of meat or fish or vegetables, so as to formready-made meals, children's snacks, sandwiches, snack foods, breakfastproducts, burger- or sausage-shaped cheese products, vegetarianproducts, spreads, pâté and cooking ingredients.

[0010] According to a third application, the invention concerns aprocess for the manufacture of products with a fibrous structurecomprised of the following steps:

[0011] a) introduction of raw materials containing whey proteins into anextruder with at least one screw;

[0012] b) transfer of raw materials from one end to the other of theextruder barrel, adjusting the screw(s) and temperature within thebarrel such that raw materials successively undergo a mixing and heatingstep up to a temperature of about 130° C., followed by a melting stepwith an increase in temperature of the material to above 130° C.,generally between 140° C. and 200° C., and an increase in pressure tobetween 0 and 50 bars, such that plasticization of the transferredmaterial takes place, especially of whey proteins;

[0013] c) extrusion at the far end of the barrel of the materialobtained after plasticization through a die adapted for texturization,shaping and cooling the material such that a product with a fibrousstructure is obtained.

[0014] The process also includes a cutting step at the outlet of thedie. According to one application, it includes a step where the productis dried at the outlet of the die after cutting to produce rehydratablefibres for food preparations if need be. It can also include a shapingstep comprised of mechanical forming processes using a shaper or mouldsor piping followed by pasteurisation and slicing, with, the productsobtained undergoing at least one of the following steps: decoration,coating, stamping, filling, frying, baking, pasteurisation,sterilisation, packaging.

[0015] According to a fourth aspect, the invention concerns amanufacturing installation for the application of the process presentedabove comprised of a screw extruder with two very similar interlockingscrews which rotate in the same direction or in the opposite directioninside a horizontal barrel, a filling device attached at the near end ofthe barrel, fitted with one or more metering devices for metered flow ofthe mixture at a predetermined rate, an extrusion die located at the farend of said barrel, thermal treatment assembly for fine-tuning thetemperature within the barrel and extrusion die, said barrel beingcomprised of:

[0016] (a) a first zone for supply of the product formula;

[0017] (b) a second zone for mixing, moisturisation where this isrequired, and heating the material up to a core temperature of at least130° C.;

[0018] (c) a third zone for melting, increasing the temperature of thematerial to over 130° C., generally between 140 and 200° C. and pressureof the material to between 0 and 50 bars, depending on the compositionof the formula, in which protein plasticization takes place, especiallyof whey proteins.

[0019] Further areas of applicability of the present invention willbecome apparent from the detailed description provided hereinafter. Itshould be understood that the detailed description and specificexamples, while indicating the preferred embodiment of the invention,are intended for purposes of illustration only and are not intended tolimit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

[0021]FIG. 1 illustrates an installation for the manufacture ofultrafibres according to a high-temperature and high-moisture extrusionprocess, according to one mode of application;

[0022]FIG. 2 illustrates an installation for the manufacture ofultrafibres according to a high-temperature and high-moisture extrusionprocess, according to another mode of application;

[0023]FIGS. 3 and 4 represent extruded fibre products after chopping, atthe outlet of the extrusion die;

[0024]FIG. 5 represents magnification of a transverse cut of an isolatedbundle of fibres as in FIG. 3 or 4;

[0025]FIG. 6 represents magnification of a fragment of product leavingthe extrusion die, with fibres shown by manual extension (×10magnification);

[0026]FIGS. 7 and 8 represent food preparations developed from extrudedfibre products incorporated into a mixture including other constituents,in particular cereals. FIG. 8 is a magnification of the core of thefibre bundle in FIG. 7.

[0027]FIG. 9 is a further magnification of a zone showing isolatedfibres in FIG. 8 (each graduation represents 1 mm).

DETAILED DESCRIPTION OF THE INVENTION

[0028] The following description of the preferred embodiment(s) ismerely exemplary in nature and is in no way intended to limit theinvention, its application, or uses.

[0029] To this end, a first aspect of the invention proposes a productobtained by extrusion baking of a mixture of dairy or cheese origin.This product has a fibrous structure with a network of macroscopicfibres whose diameters are in the order of 0.1 mm to 1 mm, ramified intomicroscopic fibres with diameters in the order of 1 μm to 0.1 mm, thedry matter in the product being at least partially obtained from whey.The dry matter in the product typically comprises 30% to 100% of drymatter originating from whey. The product consists of 15 to 50% of drymatter and typically 25 to 40%. The dry matter of the product consistsof at least 35% of total proteins. The dry matter originating from wheyincludes isolated and/or concentrated proteins, and/or dried whole whey,and/or dried whey fractions such as lactose, milk fats, lactoferrin,calcium or other milk minerals or fractions. According to oneapplication, the product contains, in addition to whey proteins, otherprotein fractions such as casein or caseinates, cheese, dried orconcentrated milk, with dry matter from the product preferably comprisedof at least 10% casein.

[0030] According to another application, the product contains, inaddition to whey proteins, non-dairy proteins chosen from amongconcentrated or isolated vegetable proteins, especially wheat, soya orpea gluten, liquid or dry egg white, with non-dairy proteinsrepresenting 0 to 70% of the mixture's dry matter, and preferably 20 to50%.

[0031] According to a second aspect, the invention concerns a foodpreparation incorporating a product in keeping with the descriptionabove added to various ingredients chosen from among cheeses, milk andderivative products (yoghurt, milk cream, milk powder, fromage blanc,butter), cereals, starches, flour, semolina, fruits and dried fruits,spices, seasoning, fats, flavouring, sugar-containing ingredients(sugar, honey), pieces of meat or fish or vegetables, so as to formready-made meals, children's snacks, sandwiches, snack foods, breakfastproducts, burger- or sausage-shaped cheese products, vegetarianproducts, spreads, pâté, and cooking ingredients.

[0032] According to one application, the food preparation has a matrixcomprised of fibres or bundles of fibres with sizes in the range of mmor μm, with the preparation having dimensions in the order of a fewcentimeters. The preparation undergoes mechanical forming, metering,shaping in moulds or piping then pasteurised and sliced. Thepreparations obtained can be decorated, stamped, cooked or pre-cooked,pasteurised, sterilised and packaged.

[0033] According to one application, the preparation contains a productin accordance with the description above which encloses a dairy ornondairy filling product. According to another application, thepreparation contains a product in accordance with the description aboveenclosed by a dairy or nondairy coating product. The preparation canalso include salts, spices, seasoning and flavouring, oil or other fats,an acidity corrector such as lactic acid. According to a thirdapplication, the invention concerns a process for the manufacture ofproducts with a fibrous structure comprised of the following steps:

[0034] a) introduction of raw materials containing whey proteins into anextruder with at least one screw;

[0035] b) transfer of raw materials from one end to the other of theextruder barrel, adjusting the screw(s) and temperature within thebarrel such that raw materials successively undergo a mixing and heatingstep up to a temperature of about 130° C., followed by a melting stepwith an increase in temperature of the material to above 130° C.,generally between 140° C. and 200° C., and an increase in pressure tobetween 0 and 50 bars, such that plasticization of the transferredmaterial takes place, especially of whey proteins;

[0036] c) extrusion at the far end of the barrel of the materialobtained after plasticization through a die adapted for texturization,shaping and cooling the material such that a product with a fibrousstructure is obtained.

[0037] Cooling takes place in the die to a temperature of 100° C.,possibly even between 80° C. and 10° C., and consists of an initialcooling phase in an uncooled zone in the die at the outlet of thebarrel, followed by a second cooling phase in a cooled zone of the die.The first cooling phase corresponds to an alignment zone of the meltedmixture which is in a viscous state and has a viscosity of 1000 to 500000 centipoises while the second cooling phase corresponds to a changeof state from the viscous state to the solid state, the linear flow rateof the product at the outlet of the die being in the order of 2 to 10m/min. Heating to 130° C. in step b) is gradual or in stages. Thetemperature can be adjusted during the process to modify the texture ofproducts. The mixture placed in the extruder is in the form of a powder,with all the required water added prior to the melting step, or inliquid or paste form.

[0038] According to one application, the whey proteins originate fromwhey protein concentrates or isolates which are 50 to 90% pure,preferably 70 to 80% pure, and also contain lactose, fats, minerals,secondary proteins of the casein macropeptide type. The process alsoincludes a cutting step at the outlet of the die such as chopping,slicing, crushing, tearing, shredding or similar to obtain choppedfibres forming flakes or bundles. According to one application, itincludes a step where the product is dried at the outlet of the dieafter cutting to produce rehydratable fibres for food preparations ifneed be. The process can also include a culinary reconstitution stepusing chopped fibres mixed with various ingredients such as cheese, milkand derivative products, cereals, starches, flour or semolina, fats,spices, seasoning and flavouring.

[0039] It can also include a shaping step comprised of mechanicalforming processes using a shaper or moulds or piping followed bypasteurisation and slicing, with the products obtained undergoing atleast one of the following steps: decoration, coating, stamping,filling, frying, baking, pasteurisation, sterilisation, packaging.According to one application, the material transferred to the die isfilled with a filling product during the extrusion step, added throughthe coextrusion valve opening into the die. The filling product can beobtained by means of an extrusion process.

[0040] According to a fourth aspect, the invention concerns amanufacturing installation for the application of the process presentedabove comprised of a screw extruder with two very similar interlockingscrews which rotate in the same direction or in the opposite directioninside a horizontal barrel, a filling device attached at the near end ofthe barrel, fitted with one or more metering devices for metered flow ofthe mixture at a predetermined rate, an extrusion die located at the farend of said barrel, thermal treatment assembly for fine-tuning thetemperature within the barrel and extrusion die, said barrel beingcomprised of:

[0041] (a) a first zone for supply of the product formula;

[0042] (b) a second zone for mixing, moisturisation where this isrequired, and heating the material up to a core temperature of at least130° C.;

[0043] (c) a third zone for melting, increasing the temperature of thematerial to over 130° C., generally between 140 and 200° C. and pressureof the material to between 0 and 50 bars, depending on the compositionof the formula, in which protein plasticization takes place, especiallyof whey proteins.

[0044] The second mixing and heating zone consists of 2 to 5 units, thethird melting zone comprises 1 to 3 units, with a screw length to screwdiameter ratio of about 10 to 33, typically between 25 and 33. Theextrusion die includes a first uncooled zone adjacent to the near end ofthe screw extruder, followed by at least one cooling zone, correspondingto an alignment zone for fibres in a viscous state and a change-of-phasezone from the viscous to solid state.

[0045] The die is connected to the barrel by means of at least one, andtypically two, adapters. The first adapter has one or two perforationsthrough which the melted and plasticized material is extruded; thesecond adapter is located between the first adapter and the extrusiondie and its function is to balance materiel pressure and flow rate. Theextrusion die has an internal shape that is adapted to the finalproduct, with size parameters designed to allow cooling of the meltedand plasticized material to 100° C., possibly between 80 and 10° C. Itsinner surface has a controlled roughness in order to exert shear forceson the product during the cooling process, the combination of coolingand shear forces leading to continuous texturization of the cooledmaterial to form fibres.

[0046] The installation can include an extrusion pump located, forexample, between the first or second interface and die for steady supplyto the die in order to stabilise product flow. This is often a gear pumpwhose body can be reheated by electrical resistances in order tomaintain a melted and plasticized mass at the required temperature.According to one application, a coextrusion valve opens into theextrusion die.

[0047] A description of a manufacturing installation for application ofthe process leading to the production of fibrous dairy products is givenbelow. The installation comprises a screw extruder 1 with two verysimilar interlocking screws which rotate in the same direction or in theopposite direction inside a barrel 2. A single screw extruder is alsopossible. Such an extruder consists of a motor 3 which drives therotation of the two screws, interlocked by means of a reduction gear ifnecessary. Rotation is powered at a rate of 25 to 100 kW for example.These screws are preferably self-cleaning and the barrel 2 can beshifted manually or hydraulically along its longitudinal line tofacilitates access to the screws. The materials used to manufacture thebarrel 2 and screws are obviously food grade materials.

[0048] A filling valve 4 is located towards the near end 5 of thebarrel. This valve 4 is used to introduce raw materials to be processedinto the screw extruder 1. The barrel can also include openings forsecondary supply along the line of the screws, for example for supply ofwater. An extrusion die 7 is located at the far end 6 of the barrel 2. Acutting device 8, and where necessary recovery device, are placed at theoutlet of the extrusion die. According to established practices, theextrusion die 7 has a smaller diameter than the bore diameter of thebarrel such that transferred materials are compressed. In the case ofcontinuous production, the installation comprises a metering device tofeed raw materials into the filling valve 4 at a predetermined flowrate. Heating 8 a and cooling devices are adjusted to regulatetemperature inside the barrel 2 and extrusion die 7.

[0049] The structure of the barrel 2 and extrusion process will bedescribed below in more detail. The term “mixture” is used to describeraw materials subjected to the steps in the process which take placeafter introduction of the materials, that is to say the heating, mixingand melting steps. The barrel 2 consists of 3 adjacent zones 9, 10, 11.The first, zone 9, is a filling zone into which the raw materials to beextruded are introduced. The filling valve 4 for the mixture opens here.According to one application, these raw materials are in the form of asolid powder and are added through the filling valve, along with water.The water for the mixture is added in the filling zone either totally orpartially, or can be added in the second zone 10. According to anotherapplication, the raw materials are in liquid form and are added throughthe filling valve 4, in the case, for example, of liquid dairy products.According to yet another application, the raw materials are in the formof a paste in the case of a cheese preparation such as ground curd,added through the filling valve, with water added in the filling zoneand/or the second zone 10 where necessary. All the water in the mixtureis added prior to the melting step. The composition of the mixture isgiven later.

[0050] The second zone 10 is where mixing, or moisturisation wherenecessary, and heating to at least 130° C. take place. The mixture istransferred from one end to the other of the barrel 2 while beingexposed to compression and shear forces, in addition to being heated, aswill be described later on. The third zone 11 is the melting zone, withthe temperature of the material increased to over 130° C., generallybetween 140° C. and 200° C., and the pressure increased to between 0 and50 bars, depending on the composition of the formula, especiallymoisture content. Thermo-mechanical treatment which takes place in thethird zone 11 is sufficient to cause the majority of food products tomelt, especially whey proteins which undergo a plasticization step. Theplasticization step and its effects on the final product will bedescribed in detail at a later point.

[0051] One application of the barrel 2 will now be described in moredetail. This involves the first 9, second 10 and third 11 zones. Thesezones include at least one 200 or 250 mm unit. Each barrel unit has aspecific, preregulated temperature. Depending on the prescribedtemperature, heating is more or less continuous and gradual. Thetemperature of each unit can be regulated during the course of theprocess, depending on the raw materials added and the products requiredat the outlet of the die. The first zone 9 is comprised of a unit 12 inwhich the temperature is equal to the autogenous temperature of themixture entering the extruder.

[0052] According to one variation, the second zone 10 has three units 13and the third zone 11 has three units 14. The temperature of the units13 in the second zone 10 is 90, 100, 140° C. respectively, from one endof the barrel 2 to the other. The temperature in the units 14 in thethird zone 11 is 165, 175, 175° C. respectively, from one end of thebarrel 2 to the other.

[0053] According to a second variation, the second zone 10 has fiveunits 13 providing gradual heating in five stages from one end of thebarrel to the other. The third zone 11 has three units 14 as in thefirst variation of the application. According to a third variation, thesecond zone 10 only has two units 13 and heating is, as a result, lessgradual than in the first and second variations. The melting zone 11 hasonly one unit 14.

[0054] In the same way as the barrel being comprised of several unitseach corresponding to a given temperature, the barrel screws alsoconsist of several elements. Each of these elements has a givenstructure, from one end to the other. The length of each series ofelements may or may not coincide with the length of a unit.

[0055] In one application, the diameter D of screw elements is 55.3 mmand the length of each element is 50, 100 or 200 mm. The total length Lof screw elements mounted on a screw shaft is 1000 mm, in other words anUD ratio of 18. This ratio ranges from 14, in the case of four 200-mmunits in the barrel, as in the third application, to 33 in the case ofnine 200-mm units, as in the second application. This ratio is, forexample, 25 in the case of seven 200 mm units. According to oneapplication, the barrel 2 of the extruder 1 consists of five 200-mmunits, four of which are heated and/or cooled to achieve a preciselyregulated temperature, notably by successive heating and heatextraction.

[0056] The elements of the single-thread screw are called V1F (pitch inmm). The elements of the double-thread screw are called V2F (pitch inmm). The elements of mixing screws are called MAL (angle in degrees)while the elements of negative-thread screws are called NEG (pitch inmm, number of perforations per thread x dimension in mm). In a usualapplication, the profile of the two screws is as follows:

[0057] 200 mm filling zone: 200 mm V2F (50 mm);

[0058] 500 mm mixing and heating zone: 100 mm V1F (50 mm)+50 mm MAL(90°)+150 mm V1F (33 mm)+50 mm MAL (60°)+100 mm V1F (25 mm) +50 mm NEG(−15 mm, 3×6 mm);

[0059] 300 mm melting zone: 150 mm V1F (33 mm)+150 mm V1F (25 mm).

[0060] This is only one example of an application of the invention.There are many more combinations of screw profiles that can beimplemented using the same screw elements or other screw elements of asimilar design. In the case of this profile, in the 500 mm mixing andgradual heating zone, the screw has elements of mixing screws andelements of the VIF screw of decreasing thread size (50 then 33 then 15mm), leading to gradual compression of treated materials.

[0061] A description of the die 7 is given below. The die 7 typicallyconsists of several die elements positioned end to end and connected bymeans of adapted mechanical attachments. Its size is adapted to providegradual cooling of the melted and plasticized material, to a temperatureof 100° C., if not less, for example to a temperature of 10° C.,preferably between 80 and 30° C. The internal surface of the die 7 has acontrolled roughness obtained, for example, by machining the internalmetal surface of the die in order to exert shear forces on the productduring the cooling process. The internal shape of the die is adapted tothe final product required.

[0062] The combination of cooling and shear forces on the walls appliedduring the liquid-to-solid change of state leads to texturization of thematerial in the form of fibres as described below. In some cases, theshear forces on the walls and the length of the die can be sufficientlyhigh to allow extrusion of the product without the need for auxiliarycooling outside the die. In the majority of cases, the die 7 includes acooling system for the outer surface, for example by circulation of coldwater in a double sleeve (water between 60° C. and 0° C.). It is alsopossible to cool the die 7 by means of brine at negative temperature(−1° C. to −20° C.). The combination of cooling temperature in the dieand shear forces on the inner walls of the die 7 is very much dependenton the shape of the die, its length, constituent materials and machiningas well as on the characteristics (temperature, moisture, . . . ) andflow rate of the melted material to be cooled down.

[0063] According to a first application, the die is a round die made of316 L stainless steel with a 325 mm² flow section allowing 100 kg/hourof material to be textured over a length of 8 m (8 zones of 1 m each).Cooling is carried out using ice water at 1° C. circulating at a rate of500 liters/hour. The moisture content of the extruded mixture is about72%.

[0064] According to a second application, the die is a rectangular diemade of 316 L stainless steel with a 1200 mm² flow section allowing 350kg/hour of material to be textured over a length of 6 m (6 zones of 1 meach). Cooling is carried out using ice water at 20° C. circulating at arate of 1000 liters/hour. The moisture content of the extruded mixtureis about 62%. The linear speed of product discharge from the die 7 isabout 2 to 10 meters/minute. The die 7 consists of a first uncooled zone15, which lengthens the far end of the melting zone 11, and at least asecond zone 16 cooled by the device above. The temperature of theproduct discharged from the die is 10 to 100° C. depending on thedesired rigidity. In a first application for example, the uncooled zone15 has a length of 2 meters.

[0065] According to one mode of application, the installation has afirst adapter between the far end 6 of the melting zone 11 and theextrusion die 7. This first adapter generally consists of one (or two)perforation(s) through which the melted and plasticized material isextruded. If there are two perforations, these converge in a singleoutlet. If the extrusion die has a small diameter, the perforations aregenerally conical. The first adapter often has two lateral perforationsinto which probes for measuring melting temperature Tm and pressure Pare inserted. The outlet of the first adapter can be round, oval,square, rectangular or with the exact internal shape of the extrusiondie (this can be a ludic shape).

[0066] According to one application, in addition to the first adapter,the extruder comprises a second adapter between the first adapter andthe extrusion die. This second adapter can have various internal shapesdepending on the internal shape of the first adapter and extrusion die.It can incorporate a diffusion plate consisting of several dozen smallperforations which distribute the flow of melted and plasticizedmaterial. In general, the total surface area of perforations in thediffusion plate is set up so as to create a restriction of 10 to 50%with respect to the flow section in the extrusion die.

[0067] According to one application, the extrusion pump is insertedbetween the second adapter and the die in order to allow steady flowinto the die for improved stabilisation of flow. Furthermore, severalcooling dies can be arranged in parallel at the outlet of the screwbarrel.

[0068] The impact of thermo-mechanical treatment in the extruder ofproducts leaving the die will now be described. Due to the hightemperatures used in the melting zone, the thermo-coagulableconstituents of the mixture undergo plasticization. The termthermo-coagulable proteins refers to proteins such as whey proteins, eggwhite, globulins, fish or meat muscle proteins as opposed tonon-thermo-coagulable proteins such as caseins or collagen. Thesethermo-coagulable proteins have the property of gelling or coagulatingaround 50-90° C. and are therefore in the form of a coagulum or solidgel at 100° C. The plasticization state is obtained at temperatures inthe range of 130 to 200° C., generally around a temperature of 145-170°C. for moisture levels during extrusion in the range of 50 to 80%,generally between 60 and 75%, and fat levels in the dry product duringthe extrusion process in the range of 0 to 40%, generally between 2 and20%.

[0069] In principle, shear forces lead to reheating by friction.Pressure in the extruder does not affect molecular interactions,particularly between proteins, but does allow high temperatures(130-300° C.) to be obtained without boiling or water vapour formationtaking place. Surprisingly, the transition of thermo-coagulableproteins, especially whey proteins, through this plasticization stageconfers on the mixture transferred to the barrel an original viscosity,probably fairly fluid, in the order of 1000 to 500 000 centipoises,which gives it a specific texture during the cooling process in the die.

[0070] It is supposed that the mixture passes through a solid state atthe beginning of zone 10, through a liquid state in the melting zone 11(viscosity of 1000 to 100 000 centipoises), a viscous state (viscosityof 100 000 to 500 000 centipoises) in the uncooled zone 15 of the die 7,an uncooled zone in which progressive alignment of the mixture intofluid fibres probably takes place, and finally through a solid state inthe cooled zone 16 of the die, a cooled zone in which fibres tendingtowards the solid state are formed.

[0071] During the plasticization process, proteins, particularly wheyproteins, undergo a change in structure with a new structure emergingunder the combined effect of the cooling and shear forces applied in thedie. The constituents of the mixture, especially whey proteins,rearrange in the form of a macroscopic and microscopic structure,consisting of superimposed layers of aligned or tangled fibres withmultiple ramifications, and possibly even fibres arranged in the form ofV-shapes. These fibres are interchangeably referred to as ultrafibres orramified network fibres in the text.

[0072] The products 17 obtained by means of the above-described processwill now be outlined. On being discharged from the die 7, the productobtained 17 prior any further treatment being carried out, for examplecutting or tearing, is in the form of a roll 18, for example cylindricalwith a diameter similar to the diameter of the die in the case of a diewith a circular section, produced continuously if a continuous processis used. This roll 18 contains a set of fibres which can be separated,for example manually, into bundles of fibres, and even individually intoultrafibres. Fibres typically have a diameter that depends on the rawmaterials used and the operating conditions within the barrel andextruder die. Before treatment such as chopping, fibres can be quitelong, in the range of several centimeters, for example 4 to 5centimeters.

[0073] Under high magnification, for example ×50, of the product 17shows that the fibre structure visible in the product at the macroscopiclevel is also found at the microscopic level. This structure is similarto a fractal, self-repeating structure, in other words fibreramifications appear to be infinite, in the same way as a hydrographicnetwork. Ramifications continue towards the infinitely small: the sameramified structure is perceived at each level of magnification. Thisextremely fine fibre structure is also similar to that of striatedskeletal muscle of mammals, consisting of a cascade of filament,microfilaments and fibrils. They are called “ultrafibres” because oftheir extremely fine structure.

[0074] At present, the largest fibres are at least 5 to 20 cm long witha diameter of 0.5 to 2 mm, if not in the order of cm for dies with adiameter of 20 to 30 mm. Associated fibres can be very small, to justwithin the limits of visual perception, in other words 1 to 2 mm longwith a diameter of 0.02 to 0.1 mm. It is assumed that this fibre networkcontinues down to the molecular level.

[0075] Depending on the composition of the initial mixture placed in theextruder and the operating conditions of the extruder, particularlytemperature and pressure conditions, a large range of aligned texturesis obtained. This fibre structure leads to Theological and organolepticproperties specific to the product and its derivatives, difficult tocharacterise instrumentally. A sample of fibres with a diameter of 30 mmand a length of 25 mm has an elasticity that is similar to that ofsynthetic viscoelastic compounds: relaxation coefficient of 60 to 90%,compared to 100% for rubber. The man skilled in the art is aware thathuman sensory perception is such that sizes in the order of 10 μm aredetected in the mouth. FIGS. 3 to 6 show the extruded product with afibrous structure.

[0076] According to one mode of application, the products leaving thedie undergo later treatment and are used as base materials oringredients for a wide range of food preparations, typicallyincorporated at a rate of 15 to 70% in these preparations. According toone mode of application, the extruded product undergoes chopping bymeans of a chopper and/or cutting, crushing, tearing, shredding, etc.,so as to obtain chopped fibres forming flakes or bundles. These flakescan be very small in size, to within the limits required for mechanicalseparation of fibres. These chopped fibres or ultrafibres are mixed witha variety of other culinary ingredients, such as cheese, milk, cereals,starch, spices and seasoning to form a mixture. The composition of thismixture varies depending on the desired fibre-based final product. FIGS.7 and 8 shows a food preparation 19 containing a matrix 20 incorporatingbundles 21. FIG. 9 shows visible fibres 22 in this matrix 20.

[0077] Derivative products include, for example, sandwiches, snacks,preparations for ready-made meals, burger- or sausage-shaped cheeseproducts. In one mode of application, the mixture is shaped, for exampleby mechanical forming in a shaper, under careful hygiene monitoring.According to another application, the mixture is shaped in piping whichundergoes pasteurisation, slicing and, in some cases, coating ordecoration steps. The resulting products can, for example, be cooked inmoulds, removed from the mould or not, then packaged. These products canalso be used as raw materials for other culinary preparations afterfrying, baking, pasteurisation, sterilisation and other steps.

[0078] A few examples are given below of derivative culinarypreparations incorporating the product obtained from the extruder, aproduct based on whey proteins and with a fibrous texture. This productis called “textured whey proteins” in the examples below.

PREPARATION EXAMPLES Preparation Example No. 1

[0079] formulation of a reconstituted steak using textured whey proteins(40%), Emmental (13%), Gouda (7%), Cheddar (5%), whole pasteurised milk(18%), cassaya starch (3%), cereal flakes (8%), sodium caseinate (2%),water (3%) and spices (1%). The preparation is mixed in a blender,shaped, decorated and browned in the oven.

Preparation Example No. 2

[0080] formulation and production of meat-free sausages using texturedwhey proteins (77%), Cheddar (10%), large-grained cassaya starch (6%),sunflower oil (3%), various other ingredients (3%) and spices (1%). Thepreparation is churned under vacuum, introduced into the piping andsteam cooked.

Preparation Example No. 3

[0081] formulation and production of breaded nuggets using textured wheyproteins (25%), Emmental (14%), Gouda (14%), breadcrumbs (13%), water(19%), potato starch (11%), milk proteins (3 %) and spices (1%). Themixture is prepared in the cutter, shaped, coated, rolled in flour andbreadcrumbs and fried in oil.

Preparation Example No. 4

[0082] formulation and production of a culinary ingredient rich in milkproteins for addition to salads, starters, savoury stuffing andfillings, soups and gratins using textured whey proteins (85%),pasteurised whole milk based spice marinade (12%), salt (1%), herbs andseasoning (2%). The preparation is churned under vacuum.

Preparation Example No. 5

[0083] formulation and production of a sweet pancake using textured wheyproteins (55%), dried fruit (12%), wheat-flour (12%), toasted cerealflakes (8%), sugar (7%), milk (5%) and vanilla extract (1%). The mixtureis prepared in the cutter, measured, decorated, cooked on a hotplate andbrowned.

Preparation Example No. 6

[0084] formulation and production of a sweet spread using textured wheyproteins (25%), yoghurt (55%), fresh fruit (12%), pistachio (4%), sugar(3%) and a gelling agent (1%). The mixture is prepared in the cutterunder vacuum and directly measured into pots.

Preparation Example No. 7

[0085] formulation and production of a full-fat savoury spread usingtextured whey proteins (15%), and/or full-fat fromage frais (80%),garlic extract (3%) and chives, salt and other spices (2%). Thepreparation is prepared by mixing with an expanding agent with injectionof gas, pumping and metering.

[0086] According to another application, it is possible to use theextruder to manufacture a stuffed food product. A food stuffing materialis introduced through a coextrusion valve 23 opening into the extruderdie. The stuffing material is, for example, added at a temperature belowabout 25° C. so as to cool down the interface with the cheese or dairypreparation extruded on the outside. The resulting product thereforeconsists of an outer layer of cheese or milk, whose texture is alignedin the direction of flow inside the die, and a food stuffing of varyingcomposition.

[0087] The coextrusion process can obviously be applied to a mixtureconsisting purely of cheese or dairy raw materials but can also beapplied to more complex formulations containing a small proportion offood ingredients of diverse origin: wheat, soya, maize, peas, rice,vegetables, etc. The stuffing can be a cheese or dairy preparation, forexample a soft cheese, or it can be a vegetable, meat, fish or seasoningbased stuffing.

[0088] It is also possible, after the extrusion/coextrusion step, tocoat the product with a coating agent such as cereals or other ediblesolids. In this way, a product consisting of three layers of innerstuffing, a cheese or dairy based envelope and a coating layer can beobtained. The shape of the product can also be modified, depending onthe cutting tool used 8, for example using a nipping cutter to produce alengthened cushion shape. In the case of a stuffing product obtained bycoextrusion, this application allows the stuffing to be entirely wrappedinside the product by mechanical processing of the product.

[0089] The raw materials used in the process will now be described ingreater detail. The composition of the mixture added to the extruder isvery similar to the product leaving the die. Water may be lost at thedie outlet in some cases as a result of evaporation (about 1 to 5%). Drymatter in the mixture consists of 30 to 100% of dry matter originatingfrom whey.

[0090] When the whey-based material is a powder introduced through thefilling zone, the powder is obtained after concentration,ultrafiltration and/or separation on preparatory chromatography columnsthen spray dried. The whey-based material introduced into the extruderin liquid form is, for example, a concentrate obtained afterultrafiltration of diafiltration of whey. In addition to the dry matterresulting from relatively dry or concentrated whey, dry matter in themixture includes, for example, fats of vegetable or dairy origin(including butter and cream), liquid or dried egg white, concentrated orisolated vegetable proteins, vegetable flour, starches, alimentaryhydrocolloids, spices and colouring. The whey can be a sweet whey fromdairy or rennet casein, or sour whey from casein processing. The amountof casein in the dry matter is low, generally under 10%, which meansdairy curds or complexes with a high proportion of casein cannot beused.

[0091] Vegetable proteins are, according to one application, wheatproteins, either pure or in the form of a mixture of glutens that can bebreaded (glutens at 70-75% of protein, depending on the amount of starchand bran remaining during extraction leading to the production of aprotein concentrate). In one application, a pea, lupin, soya or eggwhite protein solution or powder is used instead of a wheat glutenpowder.

[0092] A few examples of the detailed formulation of the mixture aregiven below.

[0093] Formulation of Mixtures:

Example 1

[0094] powdered whey protein concentrate containing 75% protein: 16%;

[0095] water: 66%;

[0096] sodium caseinate: 1.7%;

[0097] wheat protein concentrate containing 72% protein 13%;

[0098] powdered egg white: 1.1%;

[0099] complex carbohydrates: 0.5%;

[0100] milk fats: 1%;

[0101] salt: 0.4%;

[0102] flavourings and seasoning: 0.3%;

Example 2

[0103] powdered whey protein concentrate containing 30% protein: 40%;

[0104] water: 30%;

[0105] powdered ultrafiltered natural casein 3.7%;

[0106] pea protein concentrate containing 68% protein: 6%;

[0107] wheat protein concentrate containing 72% protein: 6%;

[0108] powdered egg white: 10%;

[0109] complex carbohydrates: 1%;

[0110] milk fats: 2.5%;

[0111] salt: 0.7%;

[0112] flavourings and seasoning: 0.1%.

Example 3

[0113] whey cheese containing 10% protein: 78%;

[0114] powdered whey protein concentrate containing 80% protein: 18%;

[0115] sodium casein: 1%;

[0116] complex carbohydrates: 1%;

[0117] butter: 2%.

Example 4

[0118] lactoersum liquid protein concentrate containing 30% protein:80%;

[0119] rennet casein: 3.2%;

[0120] pea protein concentrate containing 65% protein: 4%;

[0121] wheat protein concentrate containing 72% protein: 4%;

[0122] soya protein concentrate containing 67% protein: 4%;

[0123] powdered egg white: 1%;

[0124] complex carbohydrates: 1%;

[0125] milk fats: 2%;

[0126] salt: 0.7%;

[0127] flavouring and seasoning: 0.1%.

Example 5

[0128] water: 72%;

[0129] powdered whey protein isolate containing 90% protein: 9%;

[0130] calcium caseinate: 0.4%;

[0131] wheat protein concentrate containing 72% protein: 15%;

[0132] complex carbohydrates: 1%;

[0133] peanut oil: 2%;

[0134] salt: 0.6%

Example 6

[0135] water: 70%;

[0136] powdered whey protein concentrate containing 80% protein: 26.3%;

[0137] sodium caseinate: 0.3%;

[0138] complex carbohydrates: 0.9%;

[0139] butter: 2.5%.

Example 7

[0140] water: 61%;

[0141] powdered whey protein concentrate containing 82% protein: 23%;

[0142] wheat protein concentrate containing 12% protein: 13%;

[0143] powdered egg white: 1%;

[0144] spices (1%), vegetable fats (0.5%), salt (0.5%)

[0145] The description of the invention is merely exemplary in natureand, thus, variations that do not depart from the gist of the inventionare intended to be within the scope of the invention. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention.

32. A food product obtained by extrusion baking of a mixture of dairy orcheese origin which includes dry matter comprising whey proteins havingan aligned fibrous structure, the fibres forming a network ofmacroscopic fibres whose diameters are in the order of 0.1 mm to 1 mm,ramified into microscopic fibres with diameters in the order of 1 μm to0.1 mm.
 33. The product according to claim 32 wherein the dry matter inthe product consists of 30% to 100% of dry matter originating from whey.34. The product according to claim 32 comprising 15 to 50% of dry matterand typically 25 to 40%, the dry matter including at least 35% of totalproteins.
 35. The product according to claim 32 wherein the whey drymatter is selected from the group consisting of isolated proteins,concentrated proteins, dried whole whey, dried whey fractions, lactose,milk fats, lactoferrin, calcium, milk minerals, milk fractions andmixtures thereof.
 36. The product according to claim 32 furthercomprising protein fractions selected from the group consisting ofcasein, caseinates, cheese, dried milk, concentrated milk and mixturesthereof, wherein the dry matter from the product comprises at least 10%casein.
 37. The product according to claim 32 further comprisingnon-dairy proteins selected from the group consisting of concentratedvegetable proteins, isolated vegetable proteins, wheat, soya, peagluten, liquid egg white, dry egg white and mixtures thereof, whereinnon-dairy proteins represent 0 to 70% of the mixture's dry matter. 38.The product according to claim 37 wherein non-dairy proteins represent20 to 50% of the mixture's dry matter.
 39. A food preparationincorporating a product according to claim 32 added to variousingredients selected from a group comprising cheeses; milk andderivative products further consisting of fromage blanc, yoghurt, cream,butter, milk powder; cereals; starches; flour; semolina; spices;seasoning; pieces of meat; pieces of fish; vegetables; fruits and driedfruits; sugar-containing ingredients further including sugar and honey;fats and flavouring; so as to form various food products selected fromthe group comprising ready-made meals, sandwiches, children's snacks,breakfast products, cooking ingredients, snack foods, shaped cheeseproducts, vegetarian products, spreads, pâté and cooking ingredients.40. The food preparation according to claim 39 further comprising amatrix selected from the group consisting of fibres, bundles of fibres,and combinations thereof, with sizes in the range of millimeters orcentimeters, with the preparation having dimensions in the order of afew centimeters.
 41. The food preparation according to claim 39 whereinthe food is shaped by methods selected from the group comprisingmechanical forming, metering, shaping in moulds and piping, followed bypasteurisation and slicing, wherein the preparation obtained can bedecorated, stamped, cooked, pre-cooked, pasteurised, sterilised andpackaged.
 42. Food preparation according to claim 39 further comprisingan item selected from the group consisting of salts, spices, seasoning,flavouring, oil, other fats, an acidity corrector such as lactic acidand combinations thereof.
 43. A filled food preparation containing aproduct according to claim 32 which encloses a filling product selectedfrom dairy and non-diary products.
 44. A coated food preparationcontaining a product according to claim 32 enclosed by a coating productselected from dairy and non-dairy products.
 45. An extrusion baked foodpreparation comprising a dairy component including dry matter furthercomprising whey proteins with a fibrous structure wherein the fibersform a network of initial fibers whose diameters are in the order ofabout 0.1 mm to 1 mm, modified into subsequent fibers with diameters inthe order of about 1 μm to 0.1 mm.
 46. The extrusion based foodpreparation according to claim 45 wherein the dry matter in the productconsists of 30% to 100% of dry matter originating from whey.
 47. Theextrusion based food preparation according to claim 45 comprising 15 to50% of dry matter, the dry matter including at least 35% of totalproteins.
 48. The extrusion based food preparation according to claim 47comprising 25 to 40% of dry matter.
 49. The extrusion based foodpreparation according to claim 45 wherein the whey dry matter isselected from the group comprising isolated proteins, concentratedproteins, dried whole whey, dried whey fractions, lactose, milk fats,lactoferrin, calcium, milk minerals, milk fractions and mixturesthereof.
 50. The extrusion based food preparation according to claim 45further comprising protein fractions selected from the group comprisingcasein, caseinates, cheese, dried milk, concentrated milk and mixturesthereof, wherein dry matter from the product is comprised of at least10% casein.
 51. The extrusion based food preparation according to claim45 further comprising non-dairy proteins selected from the groupconsisting of concentrated vegetable proteins, isolated vegetableproteins, wheat, soya, pea gluten, liquid egg white, dry egg white andmixtures thereof, wherein non-dairy proteins representing 0 to 70% ofthe mixture's dry matter.
 52. The extrusion based food preparationaccording to claim 45 wherein non-dairy proteins represent 20 to 50% ofthe mixture's dry matter.
 53. The extrusion based food preparationaccording to claim 45 added to various ingredient selected from thegroup comprising cheeses; milk and derivative products furtherconsisting of fromage blanc, yoghurt, cream, butter, milk powder;cereals; starches; flour; semolina; spices; seasoning; pieces of meat;pieces of fish; vegetables; fruits and dried fruits; sugar-containingingredients further including sugar, and honey; fats and flavouring; soas to form various food products selected from the group consisting ofready-made meals, sandwiches, children's snacks, breakfast products,cooking ingredients, snack foods, shaped cheese products, vegetarianproducts, spreads, pâté and cooking ingredients.
 54. The extrusion basedfood preparation according to claim 45 comprising a matrix selected fromthe group consisting of fibres, bundles of fibres, and combinationsthereof with sizes less than 20 centimeters.
 55. The extrusion basedfood preparation according to claim 45 wherein the food is shaped bymethods selected from the group comprising mechanical forming, metering,shaping in moulds and piping, followed by pasteurisation and slicing,wherein the preparation obtained can be decorated, stamped, cooked,pre-cooked, pasteurised, sterilised and packaged.
 56. The extrusionbased food preparation according to claim 45 further comprising an itemselected from the group consisting of salts, spices, seasoning,flavouring, oil, other fats, an acidity corrector such as lactic acidand combinations thereof.
 57. The extrusion based food preparationaccording to claim 45 further comprising a filling selected from dairyproducts.
 58. The extrusion based food preparation according to claim 45further comprising a coating substantially enclosing the foodpreparation.
 59. A coated extrusion based food preparation comprising: afood product having a dairy component including dry matter, the drymatter including whey proteins with a network of macroscopic fiberswhose diameters are in the order of about 0.1 mm to 1 mm, ramified intomicroscopic fibers with diameters in the order of about 1 μm to 0.1 mm;and a coating substantially enclosing the food product.
 60. The coatedextrusion based food preparation according to claim 59 wherein thecoating is selected from a group comprising dairy products.
 61. Thecoated extrusion based food preparation according to claim 59 whereinthe dry matter in the product consists of 30% to 100% of dry matteroriginating from whey.
 62. The coated extrusion based food preparationaccording to claim 59 added to various ingredient selected from thegroup comprising cheeses; milk and derivative products furtherconsisting of fromage blanc, yoghurt, cream, butter, milk powder;cereals; starches; flour; semolina; spices; seasoning; pieces of meat;pieces of fish; vegetables; fruits and dried fruits; sugar-containingingredients further including sugar, and honey; fats and flavouring; soas to form various food products selected from the group consisting ofready-made meals, sandwiches, children's snacks, breakfast products,cooking ingredients, snack foods, shaped cheese products, vegetarianproducts, spreads, pâté and cooking ingredients.
 63. The coatedextrusion based food preparation according to claim 59 wherein the foodis shaped by methods selected from the group consisting of mechanicalforming, metering, shaping in moulds and piping, followed bypasteurisation and slicing, wherein the preparation obtained isdecorated, stamped, cooked, pre-cooked, pasteurised, sterilised andpackaged.
 64. The coated extrusion based food preparation according toclaim 59 enclosing a filling selected from dairy products.